The present invention relates to chest developers, and relates more particularly to such a chest developer which comprises a cylinder coupled to a fixed handle, a piston rod having one end mounted with a piston movable in the cylinder and an opposite end coupled to a movable handle outside the cylinder, and a compression spring mounted in the cylinder and stopped between the piston and one end of the cylinder.
A variety of chest developers have been disclosed for exercising the muscles of the hands and the chest, and have appeared on the market. FIG. 1 shows a chest developer according to the prior art which comprises two handles, and a plurality of coiled springs connected in parallel between the handles by clips. This structure of chest developer is not durable in use because the spirngs wear quickly with use. Furthermore, the user's fingers tend to be jammed in the springs during the operation. FIG. 2 shows another structure of chest developer according to the prior art, which comprises two foot plates fixedly connected together, a handle, and an elongated elastic member connected between the foot plates and the handle. This structure of chest developer is still not durable in use because the elastic member wears quickly with use. FIG. 3 shows still another structure of chest developer according to the prior art, which comprises a sleeve having handle at one end, a tube having one end inserted into the sleee and an opposite end terminating in a handle, and a compression spring mounted inside the sleeve and stopped against the tube. When in operation, the tube is forced toward the sleeve to compress the compression spring. This structure of chest developer is still not durable in use because the compression spring wears quickly with use.
The present invention has been accomplished to provide a chest developer which is durable and practical in use. According to one aspect of the present invention, the chest developer comprises a cylinder coupled to a fixed handle, a piston rod having one end mounted with a piston movable in the cylinder and an opposite end coupled to a movable handle outside the cylinder, a compression spring mounted in the cylinder and stopped between the piston and one end of the cylinder, and air holes made on the cylinder at two opposite ends. When the movable handle is moved relative to the fixed handle, the piston is reciprocated by the piston rod to draw air into the cylinder and then to force air out of the cylinder. According to another aspect of the present invention, an adjustment device is installed in the cylinder to adjust the flow rate of exhaust air so that the damping force against the movable handle can be adjusted as desired.